Conventional slot machines are gaming devices that incorporate a plurality of reels, typically three, rotatable about a common axis. Each reel has multiple indicia printed on the periphery depicting specific symbols relevant to game play. A player initiates a play on a slot machine by, for example, pulling a lever or depressing a triggering button. Upon initiating a play, a random number generator generates a first number, which in turn corresponds to an indicium or symbol. The first reel is then stopped to display the selected indicium. In a similar fashion, the second and third reels display indicium corresponding to second and third numbers generated by the random number generator. After the reels have stopped spinning, the microprocessor evaluates the outcome of the first, second, and third generated random numbers to determine if there is a winning combination. When a play concludes with a winning combination being displayed, a payout may be awarded to a player.
In a traditional, three reel, mechanical slot machine, each reel might have, for example, twenty-two stops or indicia that can be displayed as part of a multiple reel payline combination. The probability for paying off on a specific combination of indicia is dependent upon the number of reels in play, the number of symbols on each reel, and the number of winning symbol combinations. For instance, the lowest probability, one in which there is only one winning combination, can be mathematically represented as 1:NR where N is the number of indicia on each reel and R is the number of reels. Therefore, for a traditional, three reel, mechanical slot machine having twenty-two symbols, the lowest probability that can be obtained is 1:223 or 1:10,648. Thus, for the slot machine to be commercially viable, the maximum jackpot payable by such slot machine is limited to the amount that could be paid one in every ten thousand six hundred forty eight plays.
As today's slot machine players become more sophisticated, the market demands higher payouts and greater game variation to maintain and increase player appeal. To allow for higher purses, and still remain commercially viable, a traditional slot machine can either increase the number of symbols per reel, or alternatively add reels to the machine. Both alternatives, however, have proven undesirable effects. For example, it is difficult to provide more than about twenty-five symbols per reel because for the symbols to remain readable the diameter of the reel is too large to fit within the physical dimensions of the standard-sized slot machine. Similarly, it has been observed that slot machines having more than three reels are less appealing to slot machine players.
One alternative technique for increasing the jackpot size in slot games employs a “virtual reel,” described in U.S. Pat. No. 4,448,419 to Telnaes. In general, a “virtual reel” is a software program that allows a slot machine to increase the payout without increasing the number of reels or the number of symbols per reel. The virtual reel software program contains instructions that map a number of virtual symbols to physical symbols on the slot machine reel. For example, a virtual reel may contain forty-four possible virtual symbols with each virtual symbol corresponding to one specific physical symbol on a twenty-two symbol reel. Therefore, in this example, the virtual reel effectively raises the lowest probability that can be obtained to 1:443 or 1:85,184, which greatly increases the available largest payout.
During a typical virtual reel slot machine play, a slot player initiates spinning of the slot machine reels through any number of means, including pulling a handle. The “virtual reel” software program then randomly selects a symbol from the virtual reel, all while the physical reel is spinning and observable by the player through a display glass. A control circuit then causes the spinning reel to stop at the symbol selected by the software. Therefore, the software controls the actual outcome of the game and the physical reel merely acts as a display device.
Another alternative technique for increasing the jackpot size in slot games employs a slot machine reel with luminescent display elements. This technique is detailed in U.S. Pat. No. 6,027,115 to Griswold et al. In general, slot machines utilizing the luminescent display element technique contain reels in which “symbol regions” contain electroluminescent elements. Multiple electroluminescent elements may be arranged in each symbol region to allow a given symbol to be displayed in multiple formats, with each format representing an independent indicia for payout purposes. For example, a “7” symbol could be displayed with its outline illuminated, with interior cross hatching, with a combination of cross hatching and outline illuminated, or with different colors. Thus, each possible symbol may appear to a player to be different physical symbol, despite the fact it exists within the same physical symbol region. By utilizing this technique, or by combining this technique with a virtual reel, the designer has still greater flexibility in creating higher odds and offering a much larger payout.
One drawback to either a virtual reel or a reel containing an electroluminescent display is that the slot machine game play is still limited by the number of unique symbols that can be displayed by the physical reel. In other words, in utilizing a traditional physical reel with twenty-two symbols, a virtual reel can display, at most, twenty-two unique symbols. Similarly, while an electroluminescent reel may increase the number of unique symbols possible, the electroluminescent reel is also limited by the number of unique luminescent patterns. Still further, if the owner of the slot machine utilizing either technique wishes to change the gaming symbols, the slot machine reels must be physically replaced, resulting in extremely costly “down-time” for the machine and consequently lost revenue for the owner.
To allow a gaming machine with an infinite number of display symbols, game manufacturer's have utilized flat, rigid panel displays, (i.e., liquid crystal displays (“LCDs”), or light emitting diode (“LED”) displays) similar to a display of a computer screen. By utilizing a rigid display panel, a computer processor is able to create, display, manipulate and control a “virtual slot machine” without any mechanical spinning reels, further allowing for an infinite number of possible symbol displays and increased payouts. However, while the use of the virtual slot machine has proven popular in today's personal computer market, it has not met with much success in casinos, as a slot machine player desires the visual stimulation, and excitement of a traditional, spinning reel slot machine.